Datasheet

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STM32L431xx Functional overview
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3.15 Analog to digital converter (ADC)
The device embeds a successive approximation analog-to-digital converter with the
following features:
• 12-bit native resolution, with built-in calibration
• 5.33 Msps maximum conversion rate with full resolution
– Down to 18.75 ns sampling time
– Increased conversion rate for lower resolution (up to 8.88 Msps for 6-bit
resolution)
• Up to 16 external channels.
• 5 internal channels: internal reference voltage, temperature sensor, VBAT/3, DAC1 and
DAC2 outputs.
• One external reference pin is available on some package, allowing the input voltage
range to be independent from the power supply
• Single-ended and differential mode inputs
• Low-power design
– Capable of low-current operation at low conversion rate (consumption decreases
linearly with speed)
– Dual clock domain architecture: ADC speed independent from CPU frequency
• Highly versatile digital interface
– Single-shot or continuous/discontinuous sequencer-based scan mode: 2 groups
of analog signals conversions can be programmed to differentiate background and
high-priority real-time conversions
– ADC supports multiple trigger inputs for synchronization with on-chip timers and
external signals
– Results stored into data register or in RAM with DMA controller support
– Data pre-processing: left/right alignment and per channel offset compensation
– Built-in oversampling unit for enhanced SNR
– Channel-wise programmable sampling time
– Three analog watchdog for automatic voltage monitoring, generating interrupts
and trigger for selected timers
– Hardware assistant to prepare the context of the injected channels to allow fast
context switching
3.15.1 Temperature sensor
The temperature sensor (TS) generates a voltage V
TS
that varies linearly with temperature.
The temperature sensor is internally connected to the ADC1_IN17 input channel which is
used to convert the sensor output voltage into a digital value.
The sensor provides good linearity but it has to be calibrated to obtain good overall
accuracy of the temperature measurement. As the offset of the temperature sensor varies
from chip to chip due to process variation, the uncalibrated internal temperature sensor is
suitable for applications that detect temperature changes only.
To improve the accuracy of the temperature sensor measurement, each device is
individually factory-calibrated by ST. The temperature sensor factory calibration data are
stored by ST in the system memory area, accessible in read-only mode.
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